The Fungal Cell Wall: Candida, Cryptococcus, and Aspergillus Species

Abstract

The fungal cell wall is located outside the plasma membrane and is the cell compartment that mediates all the relationships of the cell with the environment. It protects the contents of the cell, gives rigidity and defines the cellular structure. The cell wall is a skeleton with high plasticity that protects the cell from different stresses, among which osmotic changes stand out. The cell wall allows interaction with the external environment since some of its proteins are adhesins and receptors. Since, some components have a high immunogenic capacity, certain wall components can drive the host's immune response to promote fungus growth and dissemination. The cell wall is a characteristic structure of fungi and is composed mainly of glucans, chitin and glycoproteins. As the components of the fungal cell wall are not present in humans, this structure is an excellent target for antifungal therapy. In this article, we review recent data on the composition and synthesis, influence of the components of the cell wall in fungi-host interaction and the role as a target for the next generation of antifungal drugs in yeasts (Candida and Cryptococcus) and filamentous fungi (Aspergillus).

Microglial Response to Aspergillus flavus and Candida albicans: Implications in Endophthalmitis

“…The outer layer of the C. albicans cell wall is said to be packed with mannoproteins and cross-linked to β-1,6-glucans and, unlike Aspergillus spp., α-glucan is absent from Candida spp. cell walls [31]. C. albicans has also been hypothesized to initiate its own uptake by host cells via complement proteins or complement receptors as an alternative immune evasion strategy [32].…”

“…C. albicans has also been hypothesized to initiate its own uptake by host cells via complement proteins or complement receptors as an alternative immune evasion strategy [32]. It has also been reported that these mannoproteins are glycosylphosphatidylinositol-modified during interactions with the host, allowing the activation of the immune response by masking the β-glucan layer and thereby leading to an ineffective activation of the host immune system [31]. Similarly, it has been reported that C. albicans tended to cause higher inflammatory cytokine and chemokine concentrations, along with increased neutrophils and inflammatory monocytes, compared with nonalbicans Candida infections [33].…”

Iron Assimilation during Emerging Infections Caused by Opportunistic Fungi with emphasis on Mucorales and the Development of Antifungal Resistance

“…This subsequently alters the passage of nutrients through the cell wall into the periplasmic space and to the plasma membrane. As such, the fungal cell wall represents an ideal target for antifungals [158,[167][168][169]. -glucan with notable differences in their architecture and attachments to these basal components.…”

“…For example, the cell wall of C. albicans contains β-(1,6-) linkages, while Aspergillus spp. do not [165,168,173,174]. The most important component of the cell wall is the β-1,3-D-glucan, which is synthesised by 1,3-β-D-glucan synthase.…”

“…The glycoproteins represent between 30-50% of the dry mass of the fungal cell wall, e.g., in S. cerevisiae or Candida spp. They are composed of modified N-and O-linked carbohydrates or mannan [168]. In some fungi, the mannan backbone consists of either single residues or side chains of different sugars [180,185].…”